Parmotrema Lichen

Parmelia cristifera

Parmelia cristifera Taylor, 1847, p. 165. [For full synonymy see Hale, 1965, p. 241.]

TYPE COLLECTION.—Calcutta, India, Wallich (FH-Tayl, lectotype).

DESCRIPTION.—Thallus loosely attached, light mineral gray, 10–25 cm broad; lobes broad and rotund, 12–20 mm wide; margins of lobes sorediate, the soralia linear; upper surface dull, continuous or becoming cracked with age; lower surface black and sparsely rhizinate at the center, naked and brown along the margins. Apothecia rare (not seen in Dominica), 1–5 mm in diameter; spores 13–18×26–35μ.

CHEMISTRY.—Cortex K+ yellow (atranorin); medulla K+ yellow to red, C–, KC–, P+ orange red (salacinic acid).

WORLD DISTRIBUTION AND HABITATS.—Pantropical; on trees and rocks at lower elevations (sea level to 1,500 m).

This common pantropical weed is well developed in Dominica, usually growing on palm trees. It is close to the protocetraric acid-containing P. dilatata Vainio, which has not yet been found in Dominica. Differences between the two species are cited in Hale (1965). I should add here that through a lapsus calami I listed P. gardneri Dodge as a synonym of P. cristifera, but this species should be identified with P. dilatata. At the same time, P. sieberi Dodge, which I called a synonym of P. dilatata (p. 245), is a synonym of P. cristifera.

SPECIMENS EXAMINED.—Roseau Valley, Elliott 1339 (TUR). Hale collections: 1 (35694), 2 (35633), 6 (35788), 9 (35391), 11 (35800, 35802). Roseau Botanical Garden, Evans 64 (US).